The present invention relates to a rotary perforator which can perforate a web such as a film, tape and paper at high speed and quality, wherein the maintenance of the rotary perforator can be simplified and the productivity is high, and further the present invention relates to a method for perforating the web with the rotary perforator, and furthermore relates to the web which has been perforated by the rotary perforator.
Since the rotary perforator can be operated at high speed, its productivity is high, and further the rotary perforator is advantageous in the reduction of manufacturing cost. Accordingly, it is widely put into practical use. A conventional rotary perforator is shown in FIG. 12, which is commercially available, and other rotary perforators of the prior art are disclosed in the specification of the U.S. Pat. No. 3,916,744, the official gazette of Japanese Patent Application Open to Public Inspection No. 44583/1975 (shown in FIG. 13), and the official gazette of Japanese Utility Model No. 39036/1988.
From the viewpoint of improvements in productivity, perforators must be operated at high speed and quality, and further their maintenance must be simplified. However, the conventional perforators do not meet the requirements.
For example, according to the U.S. Pat. No. 3,916,744 and Japanese Patent Application Open to Public Inspection No. 44583/1975 (shown in FIG. 13), a disk 202, the center of which is eccentric to a main shaft around which a drum 201 is rotated, is provided close to the drum 201 by which film perforation is conducted. On the disk 202, a plurality of arms 203 provided with punches are fixed onto the disk 202. When the disk is rotated in accordance with the rotation of the drum, the arm 203 is displaced radially on the disk since there is a distance between the center 205 of the drum and the center 206 of the disk. As a result, the punch section 204 mounted on the tip of the arm 203 rotated integrally with the drum 201, is linked with the arm 203, so that the punch section 204 can be swung around a predetermined shaft (not shown) which is supported so that it can be rotated integrally with the drum. Therefore, the punch section 204 is oscillated around the shaft, and perforates a film in cooperation with a plurality of dies (not shown) provided along the circumference of the drum 201 corresponding to the punch sections 204. In FIG. 13, the film is supplied from the left as shown by an arrow mark, and wound around the drum 201, and then the film advances to the right as shown by an arrow mark. Since FIG. 13 is a front view, only a portion of the punch section 204 is illustrated in the drawing.
This kind of machine is capable of conducting a high speed perforating operation. However, since the main shaft of the drum and the center of the disk are shifted, that is, the center of the disk is eccentric to the main shaft of the drum, the arm body and the punch section are not aligned on a line in some stage of the rotation of the disk which is rotated around the drum. As a result, a load is given to a portion of the arm, so that the frequency of maintenance operations is increased. Because of the aforementioned disadvantage, it is not possible to stably conduct perforation at high speed and quality.
The aforementioned disadvantage caused by the load partially given to the arm due to the eccentricity between the main shaft of the drum and the center of the disk, is solved by the aforementioned machine available on the market and also solved by the machine disclosed in the official gazette of Japanese Utility Model 39036/1988.
These machines utilize a channel cam mechanism. These mechanisms are structured in the following manner: an arm body 133 is provided to a cam groove 122 through a cam follower 131. Accordingly, the occurrence can be prevented in which an arm body 133 and a punch section 156 are not aligned on a line in the radial direction of a disk (groove cam) 121. However, even in the aforementioned machine, a load is given to the connection of the arm body and the punch section. That is, in order to improve the efficiency of force given to the punch, it is effective to increase the ratio of the distance from a shaft 152 to a roller 153, to the distance from the shaft 152 to a punch 155. However, when the ratio is increased in the aforementioned manner, dimensions of the apparatus are increased. Therefore, a load given to the roller is increased. When a play is caused in the roller, it is successively caused between the cam groove 122 and the cam follower 131. As a result, vibrations are caused in the apparatus, and accuracy of perforation is deteriorated. Consequently, it becomes difficult to carry out perforating operations at high speed and quality.
In FIG. 12, numeral 1 is a film, numeral 100 is a main body which is not rotated, numeral 111 is a drum, numeral 112 is a die which is provided along the circumference of the drum, numeral 113 is a flange which is rotated integrally with the drum, numeral 133A is a groove which receives the roller 153 connecting the arm body 133 and the punch section 156, and numeral 151 is a bracket which supports the shaft 152 of the punch section 156 and is rotated integrally with the drum 111.
In the case of the machine available on the market, the arm body 133 is brought into contact with a guide 114. Accordingly, when the groove-cam mechanism is displaced in the radial direction, the arm body 133 slides on the surface of the groove. The guide surface is flat, so that lubricating oil is not maintained in a good condition on the surface. Therefore, the arm body 133 seizes up, and it can not be slid smoothly, so that the accuracy of perforation is affected. When an excessive amount of lubricating oil is supplied to the sliding portion, there is a possibility that the supplied oil spills and stains the film surface.
The punch to carry out perforating operations is provided at the tip of the punch section 156. When the punch is worn out, it is ground down. Accordingly, the length of the punch is reduced. The punch must be set at a predetermined position so that it can be engaged with the die. However, when the length of the punch is changed, the punch position is also changed, so punch engaging accuracy is lowered. Therefore, the punching performance is deteriorated, and depending on the case, punching operations can not be carried out. When the aforementioned defective punching operations are conducted a large number of times, productivity is remarkably lowered, and it is difficult to obtain products of high quality.
FIGS. 14 and 15 show the operations of the punch 155 and the stripper 154 of an apparatus available on the market. A slide groove 158 is formed at the tip of a lever 156 illustrated in FIG. 12, and a compression spring 157 is provided into the bottom portion of the slide groove 158. Further, the stripper 154 is slidably inserted into the slide groove 158. The stripper 154 is pushed outside of the slide groove 158 by the spring 157. A stopping device (not shown) is provided so that the stripper 154 can not be excessively protruded from the slide groove 158. FIG. 14 shows a state in which the stripper 154 is brought into contact with the film 1 located on the die 112 provided on the drum 111 surface, and the punch 155 has entered the die 112 and completed a perforating operation of the film 1. The stripper 154 is separated from the film surface concurrently when the punch 155 is disengaged from the punched hole of the film, or immediately after that, so that the film 1 can not be raised when the punch 155 is separated from the die 112. However, as shown in FIG. 15, there is a possibility that the surface of the film 1 is damaged by the stripper 154 in the following manner: from when the punch 155 has perforated the film 1, to when the stripper 154 is separated from the film 1, the distance between the edge 154A of the stripper 154 and the rotary shaft 152 of the lever 156 is changed from R shown in FIG. 14 to R' shown in FIG. 15; and as a result, the stripper 154 rubs the film surface in the range from R to R' by the force of the spring 157 and the weight of the stripper 154. Further, in the process in which the stripper 154 is brought into contact with the film 1 and presses the film 1 against the die 112, there is a possibility that the same problem is caused. At worst, the film 1 is displaced from the appropriate position on the die 112, and can not be perforated appropriately.